Console error when saving current Playground project

[kerrywei]

Describe the bug A clear and concise description of what the bug is.

To Reproduce Steps to reproduce the behavior:

1. launch a brand new playground page
2. open developer console
3. click 'Save' button
4. you will see errors from console. see screenshot below

Expected behavior No errors when trying to save a playground project

Desktop (please complete the following information):

• OS: Mac OS X 11.6.1 (20G224)
• Browser: Chrome
• Version 96.0.4664.110 (Official Build) (x86_64)